分类： 物理学 >> 核物理学 提交时间： 2023-10-06
摘要： To correct spectral peak drift and obtain more reliable net counts, this study proposes a long-short memory (LSTM) model fused with a convolutional neural network (CNN) to accurately estimate the relevant parameters of a nuclear pulse signal by learning of samples. A predefined mathematical model was used to train the CNNLSTM model and generate a dataset composed of distorted pulse sequences. The trained model was validated using simulated pulses. The relative errors in the amplitude estimation of pulse sequences with different degrees of distortion were obtained using triangular shaping, CNN-LSTM, and LSTM models. As a result, for severely distorted pulses, the relative error of the CNN-LSTM model in estimating the pulse parameters was reduced by 14.35% compared with that of the triangular shaping algorithm. For slightly distorted pulses, the relative error of the CNN-LSTM model was reduced by 0.33% compared with that of the triangular shaping algorithm. The model was then evaluated considering two performance indicators, the correction ratio and the efficiency ratio, which represent the proportion of the increase in peak area of the two characteristic peak regions of interest (ROIs) to the peak area of the corrected characteristic peak ROI and the proportion of the increase in peak area of the two characteristic peak ROIs to the peak areas of the two shadow peak ROI, respectively. Ten measurement results of the iron ore samples indicate that approximately 86.27% of the decreased peak area of the shadow peak ROI was corrected to the characteristic peak ROI, and the proportion of the corrected peak area to the peak area of the characteristic peak ROI was approximately 1.72%. The proposed CNN-LSTM model can be applied to X-ray energy spectrum correction, which is of great significance for X-ray spectroscopy and elemental content analyses.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Baoliang Ge
Qing Zhang
Rui Zhang
Jing-Tang Lin
Po-Hang Tseng
Che-Wei Chang
Chen-Yuan Dong
Renjie Zhou
Zahid Yaqoob
Irmgard Bischofberger
Peter T. C. So
摘要： Polarization light microscopes are powerful tools for probing molecular order and orientation in birefringent materials. While a multitude of polarization light microscopy techniques are often used to access steady-state properties of birefringent samples, quantitative measurements of the molecular orientation dynamics on the millisecond time scale have remained a challenge. We propose polarized shearing interference microscopy (PSIM), a single-shot quantitative polarization imaging method, for extracting the retardance and orientation angle of the laser beam transmitting through optically anisotropic specimens with complex structures. The measurement accuracy and imaging performances of PSIM are validated by imaging a rotating wave plate and a bovine tendon specimen. We demonstrate that PSIM can quantify the dynamics of a flowing lyotropic chromonic liquid crystal in a microfluidic channel at an imaging speed of 506 frames per second (only limited by the camera frame rate), with a field-of-view of up to $350\times350 \mu m^2$ and a diffraction-limit spatial resolution of $\sim 2\mu m$. We envision that PSIM will find a broad range of applications in quantitative material characterization under dynamical conditions.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Han-Tang Lin
Wen-Ping Chen
Jinzhong Liu
Xuan Zhang
Yu Zhang
Andrew Wang
Shiang-Yu Wang
Matthew J. Lehner
C. Y. Wen
J. K. Guo
Y. H. Chang
M. H. Chang
Anli Tsai
Chia-Lung Lin
C. Y. Hsu
Wing Ip
摘要： We present detections of stellar flares of Wolf\,359, an M6.5 dwarf in the solar neighborhood (2.41~pc) known to be prone to flares due to surface magnetic activity. The observations were carried out from 2020 April 23 to 29 with a 1-m and a 0.5-m telescope separated by nearly 300~km in Xinjiang, China. In 27~hr of photometric monitoring, a total of 13 optical flares were detected, each with a total energy of $\gtrsim 5 \times 10^{29}$~erg. The measured event rate of about once every two hours is consistent with those reported previously in radio, X-ray and optical wavelengths for this star. One such flare, detected by both telescopes on 26 April, was an energetic event with a released energy of nearly $10^{33}$~erg. The two-telescope lightcurves of this major event sampled at different cadences and exposure timings enabled us to better estimate the intrinsic flare profile, which reached a peak of up to 1.6 times the stellar quiescent brightness, that otherwise would have been underestimated in the observed flare amplitudes of about $0.4$ and $0.8$, respectively, with single telescopes alone. The compromise between fast sampling so as to resolve a flare profile versus a longer integration time for higher photometric signal-to-noise provides a useful guidance in the experimental design of future flare observations.
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